1. Field of the Invention
The invention is directed to a method and apparatus for washing particulate matter away from an apparatus within a horizontal section of a deviated subterranean well together with means for washing particulate matter away from remedial tubing as such tubing is thereafter retrieved to the top of the well. The washing apparatus and method used during the retrieval of the remedial tubing to the top of the well may be used independently of the apparatus for washing around the exterior of the apparatus when said apparatus is within the horizontal section of a deviated well.
2. Description of the Prior Art
In the past, those skilled in the art relating to remedial operations associated with the drilling, production and completion of subterranean oil and gas wells have relied on conventional "snubbing" or hydraulic workover units which utilize threaded or coupled remedial tubing normally inserted through production tubing for use in operations, such as perforating, acidizing and fracturing, corrosion control, pressure testing of tubular goods and vessels, cementing, clean out operations, sand bridge removal, storm valve recovery, insertion of kill strings, wireline tool fishing, and the like.
Continuous coiled remedial tubing and injectors for use therewith have contributed substantially to conventional remedial tubing operations. For example, coil tubing, being continuous, can be inserted into the well faster than threaded and coupled tubing which is furnished in relatively short sections that must be screwed together. In addition, it is easier, when required, to pass continuous tubing through stuffing boxes and blowout preventers because its external diameter is consistently the same size and not interrupted periodically by couplings. The coiled remedial tubing normally is made of steel and is commercially available in sizes from 0.75 inch o.d. through 1.315 inch o.d., but may have a smaller or larger diameter. Typical of such remedial coil tubing and injectors is that generally described in U.S. Pat. No. 3,182,877. The apparatus is commercially referred to as the "Bowen Continuous Spring Tubing Injector Unit" and basically comprises a hydraulically powered injector unit which feeds a continuous remedial tubing string from a coiled or "spooled" workstring contained on a powered and generally portable reel unit into the wellhead by means of two opposed, endless, rotating traction members. Such a reel unit is generally described in U.S. Pat. No. 3,614,019. The upper end of the string which remains on the reel is conventionally connected to the hollow shaft of the reel which permits a liquid or a gas to be pumped through the coiled remedial tubing string by means of a swivel connection. The injector and reel are normally mounted on a single transportable skid, a trailer, or, alternatively, may be componently arranged on skids to facilitate convenient offshore use.
To inject remedial coiled tubing, the injector is arranged on or above the wellhead. The reel unit, containing up to approximately 15,000 feet of continuous coiled metal remedial tubing, is located preferably about 15 to 20 feet from the wellhead. The remedial coiled tubing is brought from the reel in a smooth arc loop through the injector unit and into the well through pressure retention and control equipment.
For many years the desirability of utilizing a subterranean wellbore having a non-vertical or horizontal portion traversing a production formation has been known and appreciated in the prior art. Laterally directed bores are drilled radially, usually horizontally from the primary vertical wellbore, in order to increase contact with the production formation. Most production formations have a substantial horizontal portions and, when conventional vertical wellbores are employed to tap such production formations, a large number of vertical bores must be employed. With the drilling of a wellbore having a non-vertical or horizontal portion traversing the production formation, a much greater area of the production formation may be traversed by the wellbore and the total field of drilling costs may be substantially decreased. Additionally, after a particular horizontal wellbore has produced all of the economically available hydrocarbons, the same vertical wellbore may be re-drilled to establish another horizontal portion extending in another direction and thus prolong the utility of the vertical portion of the well and increase the productivity of the well to include the total production formation.
By use of and reference to the phrase "wellbore" herein, it is intended to include both cased and uncased wells. When uncased wells are completed, the bore hole wall defines the maximum hole diameter at a given location. When cased wells are completed, the "wall" of the well will be the internal diameter of the casing conduit.
By use of the phrase "deviated well" and "deviated wellbore", it is meant to refer to wells and wellbores which comprise a vertical entry section communicating through a relatively short radius curvature portion with a non-vertical or horizontal portion communicating with the production formation. In most instances, the production formation extends for a substantial horizontal extent and the generally linear wellbore portion traverses a substantial horizontal extent of the production formation, at least up to a distance of 1000 to 2000 feet, or more. The radius portion of the wellbore has a curvature of at least 10.degree. per 100 feet of length, and preferably a curvature lying in the range of 10.degree. to 30.degree. per 100 feet of length.
In such deviated well bores, particularly those having the longer lengths, fracturing fluids can be expected to be introduced into the linear, or horizontal, end portion of the well to frac the production zone to open up production fissures and pores therethrough. Such action will result in particulate matter flowing into the wellbore, particularly from top to bottom, through perforations within the casing, such that it will become difficult, if not impossible to laterally move devices through the production tubing which are required for certain completion operations in such linear or horizontal end portion of such wells. Because of the horizontal nature of such linear end portions of such wells, such material can be expected to gravitate, collect, and compact, particularly on the downward-most side and within the production tubing. It would then be desirable to first break up such compaction by providing a suspension of such particulate matter within the washing, or other, fluid, and thereafter circulate such suspended particulate matter to the top of the well, for removal.
As remedial tubing is introduced into the well through the production tubing, in such deviated horizontal wells during the completion operation, it is to be anticipated that particulate matter, such as sand, gravel packing materials, or the like, will become compacted exterior of the remedial tubing such that upon upward longitudinal manipulation of the remedial tubing subsequent to the remedial activity, it will be difficult, if not impossible, to remove the remedial tubing from within the production tubing. In addition to the washing portion of the apparatus described above, the present invention also provides means for injecting a wash fluid through the remedial tubing and directing such injected wash fluid upwardly and frontally toward the remedial tubing in a radial fashion to wash the impacted particulate matter around the remedial tubing away therefrom to permit such tubing to be retrieved, freely, to the top of the well without interference with the impacted particulate matter which has settled around the remedial tubing during the particular completion operation.